Alternating-current relay



March 22, 1927.

' 1,621,533 D. GRIMES ALTERNATING CURRENT RELAY Filed Dec.'29. 19211250' 2 9 I 5/ I'l Q: 45 20 44 I6 19 r;

' IINVENTOR fi. firm; BY

6 ATTORNEY Patented Mar. 22, 1927.

UNITED STATES PATENT OFFICE.

DAVID GRIMES, OF 'IOMPKINSVILI E, NEW YORK, ASSIGNOR TO A IEBICAN TELE-PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

ALTERNATmG-CURRENT RELAY.

Application filed December 29, 1921. Serial No. 525,726.

The principal object of my invention is to provide a new and improvedrelay adapted to respond selectively to feeble alternating currents of aparticular frequency. An-

other object of my invention is to provide a relay adapted to actuate aringer on attenuated alternating currents of frequency 135 cycles persecond as received over long tele phone lines. Still another object ofmy in- 1 vention is to provide a feed-back system by which energy may besupplied from a local battery to intensify the vibration of. a tunedreed in an alternating current relay. These-objects and other objects ofmy invention will become apparent upon consideration of a specificexample which I have illustrated in the accompanying drawings and whichI will now proceed to describe in the following specification. It willbe understood that the invention is defined in the appended claims.

Proceeding to a description of the relayas shown in the drawing, theconductors 11 bring the signaling current of 135 cycles frequency persecond from a long telephone line to the magnet coils 12. Thealternating magnetic flux enerated thereby actsv upon the tunedpolarized reed 13 tending to make it vibrate. At the end of the reed onone side is a stop 14and on the other side a con.- tact 15 from which apartial circuit may be traced through the resistance 16 and condenser 17to ground 18. Branching from this circuit at a point between theresistance 16 and the condenser 17 is a branch circuit through theresistance 19 and device 20 to ground 21.

A microphonic' device, consisting of powdered carbon 22 between theplates 23 and 24, has one of its plates 23 fixed on the reed 13 near itsbase. The other plate 24: is attached to the member 25, which may beeither a fixed support or a-free inertia support. Fromthe member 25there isa conductive connection through a resistance 26 to one side ofthe line 11.

From the block 27, which supports the reed 13, there is a conductiveconnection through the battery 28 to the other side of the line 11,which is grounded at 29. The condenser 30 i interposed in the side ofthe line connected to the resistance 26. 31 is a phase shifter, by whichthe phase relation may be adjusted between the resistance variations inelement 22 and the current variations in winding 12.

Alternating current coming in over the line 11 passes through thewindings 12, and,

if of proper frequency, sets the/reed 13 in vibration. The vibration ofthe reed 13 var1es the pressure on the carton granules 22 and thusvaries the resistance of the circuit of battery 28, this circuit beingtraced as follows: 28-2713232224-2526 12. A condenser30 is provided tokeep the current from battery 28 off the line.

. Then the resistance of the microphonicelement 22 is unvarying, thecurrent from the batery 28in the coils 12 produces a stress on the"polarized reed 13, but no vibration. But the variation of resistance of22 var es the current from battery 28 to they coils 12, and thisvariation is in such phase relation with the alternating current comingin over the line 11, that the action of the magnets 12 on the reed 13 isaccentuated. Hence it will be seen that an initial vibration caused bythe alternating'current comin /in over the line 11 causes a feed backvariation of energy from the battery 28 that builds up the vibration ofthe reed 13.

This vibration of the reed 13 causes it I intermittently to make contactwith the member 15. When a contact is made in this way the condenser 17is charged through a circuit traced as follows: 292827-- 13-15.16-17j18.Such charge will be completed during'the period of cont-act between thereed 13 and the member 15. A discharge current from the condenser 17will then pass through the resistance 19 and device 20 to ground 21.This will build up so slowly that it will not be of considerablemagnitude at the time the contact is broken at 13-45, but the dischargewill be practically completed by the time this contact is made again.

Thus the condenser 17 will be charged 135 times er second and dischargedas often through t e device 20. The integrated current from the.condenser 17 through the device 20 at this frequency of 135 cycles persecond will be suflicient to actuate the device20. m

The microphonic button 23.2224 should 'be attached near the baseendof'the reed where it will have very little damping effect.However,'in so far as it tends to damp the vibration of the reed thisefi'ect will be more/than compensated by the deed-back of local energy.'Of course the moun ing of the button on then-eed may change he' naturalfrequency of the reed, but the dimensions of the reed may then beadjusted so as to give it the desired frequency when it carries thebutton.

What is claimed is: 1. In an alternatingi current relay a local sourceof energy an means governed by the relay armature to apply this energyto the armature in phase'wlt to the relay;

2. In an alternating current rela of the vibratory reed type, a localsource 0 energy, means to apply such energy to exert a vibrator tendencyon the reed, and a, device attac ed to the reed to control said means.

3. In an alternating current relay of the vibratory reed type, a localbattery, a microphonic element associated with the reed and m circuitwith the battery, and means to incoming energy mamas? tact associatedwith the reed and a phase adjustor to make the local battery energycoincide in effect on the said reed with ourrent of appropriatefrequency to the reed received on said telephone line.

5. In an alternating current relay of the vibratory reed type, a localbattery, a microcircuit with the battery, and circuit conmotions to putthe battery current controlled by the button through the relayifisuperposition to the normal line current therethrough.

- In testimony whereof, I have signed my name to this specificationthis-28th day of December, 1921;

DAVID GRIMES.

phonic button mounted on the reed and in i

